Free, in your browser
Time your contractions
One tap when it begins, one tap when it fades. All the maths happens in this browser. Nothing is uploaded and there is no account.
Early labor
Nothing timed yet.
Tap the button when a contraction begins, and again when it fades. Everything is worked out here, in this browser.
Every number on this page is worked out in your browser. Nothing is uploaded, there is no account and there are no cookies. Your log is kept in this browser on this device, so it survives a reload, and you can wipe it with Clear everything.
Your log 0
Nothing timed yet. The first tap starts the first one.
| # | Started | Lasted | Apart | Actions |
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What is the 5-1-1 rule?
The 5-1-1 rule is what many providers give as a signal to call: contractions coming every 5 minutes or less, each lasting 1 minute or more, and that pattern holding for 1 full hour. All three at the same time. Four contractions five minutes apart is not 5-1-1, because 5-1-1 also asks for the hour.
Some providers give 4-1-1 instead, which is the same shape with a four minute gap. The timer below lets you pick which one you were given, and it measures all three parts either way. Your provider's instructions win over any rule of thumb, and over this page.
Email this log to yourself
You will be asked to read these numbers out, and reading them off a phone with a contraction going is hard. Put your address in and the log lands in your inbox as plain text, ready to forward or read. It goes to you and to nobody else, and we do not keep a copy. You do not need an account and you do not need to do this to use the timer.
Stored on our own server, never sold, never shared. Your IP is hashed, not kept. Nothing about your pregnancy is asked for or stored.
Wavesong is not a medical device and does not give medical advice. It shows the pattern you timed against the rule you picked. It never says you are in labor.
Call your provider or your maternity unit now, whatever this page shows, if your water breaks, if you are bleeding, if you have constant severe pain with no relief between contractions, if your baby is moving less than usual, or if you are under 37 weeks and think you might be in labor.
How this decides, in plain words
It is worth knowing what the timer is doing, because the whole point is that you can check it. There are three numbers and they are measured separately.
How often
Measured start to start, from the moment one contraction begins to the moment the next begins. That is how the interval is counted in obstetrics. Measuring end to start instead stretches every gap by exactly the length of a contraction, which is enough to move you a whole phase in the wrong direction.
How long
The average length of the contractions inside the window. A contraction still running is not counted, because it does not have a length yet. A double tap that produces a zero length contraction is thrown away rather than dragged into the average.
For how long
How long the current session has been running, measured to the last thing you timed and not to the clock. Leaving the tab open on a table does not grow this number. This is the part of the rule most timers skip.
The averages are taken over a sliding window that lasts exactly as long as your rule asks the pattern to hold, so for 5-1-1 that is the last hour. Averaging over the whole hour is what stops ten good minutes from tripping the rule. And there is a fourth thing that is not a criterion but a guard: if nothing new has been timed for more than two of your rule's intervals, the pattern reads as paused rather than met. Without that, a session that met the rule and then stopped would keep saying so half an hour later.
This is the same model the app runs, ported line for line. It is not a similar idea, it is the same arithmetic: the JavaScript on this page is checked against the compiled engine from the app across 154 cases and 6006 fields, and the current difference is 0.00. What you see here is what you would see there.
Why this one counts the hour when most do not
On 24 August 2026 we downloaded the browser contraction timers that rank for this search and read the JavaScript they serve. Two of the strongest tell you to head in without ever checking the third part of the rule.
| Tool | What its own code requires before it says go | The hour? |
|---|---|---|
| yourduedate.com | Average gap under 5 minutes, average length over 60 seconds, and 4 contractions. About fifteen minutes of data. | Not checked |
| mycontractiontimer.com | Average gap under 200 seconds, average length over 55 seconds, and 3 contractions. About seven minutes of data. | Not checked |
| Wavesong, this page | All three parts of your rule met at the same time, averaged over the full window, and the pattern still running. | Measured and shown |
This is not a small difference. The leading contraction timer on the App Store has one star reviews about exactly this, in the mother's own words: "the last number in a 411 or 511 contraction timing is for one hour". Being sent in on three contractions is how you end up in triage at 2 a.m. and sent home again.
Nothing here leaves your browser
This page loads one stylesheet and two scripts, all from this domain. It sets no cookies, loads nothing from any third party, and has no analytics on it. There is no server that could see your contractions, because the maths runs in your browser.
Your log is saved in this browser, on this device, so that reloading the page at three in the morning does not wipe forty minutes of work. That is browser storage, not a cookie, and it is not readable by us or by anyone else. Clear everything wipes it. The only way anything leaves this page is if you type your address into the box above and ask us to email the log to you, and then it goes to you and we keep no copy.
How Wavesong helps you see the pattern
This page is the timer. The app is the same model with the parts a browser tab cannot do: a Live Activity so the pattern is on your lock screen without unlocking anything, an Apple Watch face you can tap without finding your phone, a widget, a summary you can hand to your midwife, and a screen built to be read at 3 a.m. with the brightness at its lowest. No ads, ever.
Not on the App Store yet. The price is on the home page and in pricing.md, and there is no trial because this page is the trial.
Where this comes from
- ACOG, How to Tell When Labor Begins. True labor contractions come at regular intervals, get closer together over time, and each lasts about 60 or 90 seconds. If rest and hydration make them go away, they are not true labor contractions.
- MedlinePlus, Am I in labor?. Contact your provider right away for regular painful contractions every 5 to 10 minutes for 60 minutes, or contractions lasting 60 to 90 seconds. This is the closest a primary source gets to the shape people call 5-1-1.
- NHS, Signs that labour has begun. Call your midwife or maternity unit for guidance if you think you are in labour or you are having regular contractions coming every 5 minutes or more often.
Questions about timing contractions
Do I measure from the end of one contraction to the start of the next?
No. The gap is counted start to start, from the beginning of one contraction to the beginning of the next. This timer does that for you, so all you have to do is tap when each one begins and ends.
It matters more than it sounds. If you count end to start instead, every gap comes out longer by the length of a contraction. With minute long contractions that turns a real four minute pattern into a reported five, which is the difference between two answers.
How many contractions do I need before this means anything?
Enough to fill the window your rule asks for. For 5-1-1 that is an hour of them, which is usually twelve or more. The tool will show you the frequency and duration from the second one onwards, but the third part of the rule cannot be met before an hour has passed, and this timer will not pretend otherwise.
What if my provider gave me 4-1-1, or something else?
Tap 4-1-1 above the criteria and everything is measured against that instead. Your provider's rule wins. If you were given something this timer does not offer, use the raw numbers it gives you, the average length and the average gap, and read them out. Those two numbers are what you will be asked for either way.
I stopped for a while and now it says paused. Is that a bug?
No, that is the point. A rule that asks for an hour of a pattern is asking for a pattern that is still going. If nothing new has been timed for more than two of your rule's intervals, this reads as paused rather than met, so a session that met the rule and then faded does not keep telling you to call an hour later.
Does this work on a phone with no signal?
Once the page has loaded, yes. There is no server call in the timing at all, so a hospital corridor with no bars changes nothing. The only thing that needs a connection is emailing the log to yourself.
Will my log survive if I close the tab?
Yes, in the same browser on the same device. It is kept in that browser's own storage and nowhere else, so it survives a reload or a crash. It does not follow you to another phone, because that would mean sending it somewhere, and nothing here is sent anywhere.
Is this a substitute for calling anyone?
No. It is a way to have real numbers in front of you when you call. Call your provider or your maternity unit if you think you are in labour, if your water breaks, if you are bleeding, if your baby is moving less than usual, or if you are under 37 weeks, whatever this page says.
Keep reading
- The 5-1-1 rule: what the three numbers actually ask for. Why the third number is the one that gets skipped.
- Braxton Hicks or labor: how to tell them apart while it is happening. The test ACOG gives, and what the timer can and cannot settle.
- When to go to the hospital in labor: the call, the drive and the timing. Going too early and going too late are different mistakes.
- Contraction timer app: what to look for before you install one at 38 weeks. Ads, paywalls and pattern alerts, measured across the vertical.
Last checked 2026-08-24